The present invention arises as a result of a need for an improved slide bearing or wear pad arrangement for the tilting and sliding bed of a vehicle of the type disclosed in U.S. Pat. No. 3,430,792 and in the above-referenced copending application.
In the prior art, metal-to-metal slide bearings have been utilized in the above-stated environment but tend to wear rapidly or seize unless well lubricated. Consequently, frequent replacement of the metal wear pads is necessitated by grinding off the remainder of the worn pad and welding on a new one. This is quite costly and time-consuming.
The use of rollers as bearing means for the sliding vehicle bed has also been proposed, but due to high stress concentration as a result of line contact between the roller and straight moving beam peening and bending of the beam flange tends to occur and the arrangement is not satisfactory.
Another prior art expedient shown in the referenced copending application involves the use of phenolic dry lube wear pads which are superior to the other prior art means in terms of load distribution and minimized friction. However, as disclosed in the prior application, the servicing and removal of the phenolic wear pads requires the removal of fastener elements which pierce the wear pads and still requires the removal of the truck sliding bed, as do all of the above prior art arrangements. This results in valuable down time for the truck and is generally inconvenient, time-consuming and unduly costly. Also, the fasteners which pierce the prior art phenolic wear pads substantially reduce their useful life because of the removal of material from them to accommodate the fasteners and a reduction in their effective thickness.
It is the object of this invention to eliminate completely the drawbacks of the prior art by providing a simplified and efficient phenolic wear pad containment which does not necessitate piercing the wear pads with fasteners and merely allows the pads to be held captive between the flanges of the sliding vehicle bed and relatively stationary but readily removable retainer elements which prevent displacement of the wear pads as the sliding bed moves relative to them. When shimming or replacing worn wear pads, there is no need to remove the vehicle sliding bed and it is only necessary to remove a pair of bolts from each wear pad containment and then remove a pair of upper wear pad retainers in order to free both the upper and lower phenolic wear pads from the containment. The sliding bed can be relieved of weight during the wear pad servicing operation by using the vehicle hydraulic system or external jacking means.